Contamination by microorganisms is one of this most troublesome problems encountered today and there is often a need to sterilize devices such as medical instruments and the like.
In U.S. Pat. Nos. 4,169,123 and 4,169,124 methods are disclosed of cold gas sterilization using hydrogen peroxide gas of temperatures below 80.degree. C. The liquid hydrogen peroxide is vaporized and the hydrogen peroxide vapor is then introduced into the sterilization chamber by pressure differential.
U.S. Pat. No. 4,642,165 discloses a method of injecting and vaporizing successive increments of a multicomponent liquid such as an aqueous solution of hydrogen peroxide, for delivery into a vacuum chamber. The vacuum in the chamber draws the multicomponent vapor into the chamber.
U.S. Pat. No. 4,512,951 discloses a method of liquid contact hydrogen peroxide sterilization. Goods to be sterilized are maintained in the sterilization chamber at a temperature below the dew point of the vapor sterilant. An aqueous solution of hydrogen peroxide is vaporized and passed into the evacuated sterilization chamber where, upon contact with the goods, the vapor condenses to form a liquid layer of sterilant on the goods. A vacuum in the chamber draws the vapor into the chamber.
United Kingdom Patent No. 1,582,060 discloses a similar liquid contact hydrogen peroxide sterilization method operated without a vacuum chamber. Liquid hydrogen peroxide is pumped through an ultrasonic spray nozzle which is operated by a stream of dehydrated air. A mist of hydrogen peroxide is sprayed into a container and mixed with hot air to change the mist into a vapor. The vapor is piped into a nonpressurized sterilization chamber where it condenses on a cool moving web of material. A stream of hot air in an adjacent chamber removes the hydrogen peroxide layer from the web. The stream is then passed to a water separator where it is relieved of the sterilant.
In some other prior art systems, when the object such as a medical instrument has been sterilized, it must be removed from the sterilization chamber and handled in some form to be prepared for and transported to the medical facility for use. For instance, with the use of endoscopes which have multiple hollow tubes therein for air, water, vacuum and the like, the endoscope is placed in a container and input and output fluid connections are made to the appropriate endoscope connections and the chamber is sealed. A sterilizing fluid is introduced into the chamber through one port where it not only surrounds and bathes the endoscope with the sterilizing agent, but is also passed through the hollow tubes of the endoscope by applying a vacuum on the other port, thus sterilizing the interior of any tubes.
However, the endoscope may still have moisture on it and the ambient air may then enter the chamber after the sterilization process or the endoscope may simply be removed from the chamber and placed in ambient air so that it will dry before use.
Such a system is inherently dangerous since any handling of the endoscope after sterilization or exposing it to ambient air after sterilization provides opportunity for recontamination of this endoscope. Further, it may continue to have moisture on the interior thereof which may contain contaminants that could be injected into the next patient with whom the endoscope is to be used.
These disadvantages of the prior art are overcome by the present invention which includes a sealable cassette in which the endoscope or other medical device is placed. The cassette has input and output fluid sealing ports for the introduction and removal of a sterilizing fluid. The endoscope or other medical instrument, if hollow, is coupled either to the input or output port. The cassette is formed of two identical halves which are placed in superimposed sealable relationship with each other to form a hollow chamber. A latch is placed on one or more handles on the cassette to create a presealing condition to allow a vacuum to be introduced at the outlet port.
The cassette is then placed in an outer oven-like container or warming chamber where the temperature is properly maintained. Connections are made to open the input and output ports on the cassette such that the sterilizing agent may be introduced through a first port to bathe the outside of the medical instrument or other object, such as an endoscope, while one end of the hollow object, such as the endoscope, is coupled to the output port where a vacuum is supplied external to the cassette to pull the sterilization agent into the cassette and through the interior passageways of the endoscope. When the sterilization process is completed, the warming chamber is opened and the sterilizing cassette is simply removed from the chamber with the input and output ports being uncoupled from their respective sources. A tight seal is maintained and the object remains in the sterilized interior of the cassette until the cassette is opened or the device is to be used. It can be stored, transported and handled without adversely affecting the sterilization of the object therein.
The two identical halves of the cassette may be bowl shaped for mating contact with each other to form the hollow chamber. A center support device formed in each bowl-shaped container section for mating contact with the center support of the mating bowl-shaped container section to prevent opposing container walls from collapsing under a vacuum. The bowl-shaped container sections can be one piece molded from a clear plastic so that the object contained therein can be observed without breaking the fluid-tight seal. The clear plastic can be a polycarbonate such as a product sold under the trademark "LEXAN". The center support means may have a hollow oval shape so that small objects such as endoscope parts could be placed therein. The oval support has an opening therein allowing the sterilizing agent to pass into it assuring sterilization of all internal surfaces and for sterilizing the small endoscope parts which may be placed therein. The center support means could be a hollow cylindrical shape or a solid cylindrical shape if desired. Each of the bowl-shaped container sections has a port with a check valve therein for providing a fluid seal that can be opened to deliver or receive a sterilizing fluid or provide a means of evacuation and closed to provide a fluid-tight seal to maintain sterilization within the cassette after the sterilization process is completed.
The cassette may also have first and second spaced concave and convex dimples on the external surface of the cassette outer walls such that when one cassette is stacked on another, the convex dimples on one cassette outer wall mate with the concave dimples on the other cassette outer wall so as to enable the cassettes to maintain their stacked relationship. A flat surface is formed around the perimeter of each cassette container section. A compressible seal is placed on the flat surface perimeter and at least one seal causing device is associated with the first and second container sections for forcing the container sections toward each other to compress the seal and form a fluid-tight seal between the first and second container sections. The container sections may also have a plurality of spaced convex ribs formed on the outer side of each molded container wall to strengthen the container walls to resist collapsing under a vacuum.
Some objects such as endoscopes have multiple elongated lumens with each lumen having a proximal end terminating in a port and a distal end. A connector is used inside the cassette to couple the proximal end ports of the lumens to one of the input and output ports on the interior of the cassette such that a sterilizing fluid passing from the input port to the output port passes through the lumens of the endoscope for complete sterilization.
Further, a tray is formed for holding the endoscope in the cassette. Clip devices are attaches to the tray to hold the outside surfaces of the endoscope in spaced relationship with each other to minimize contact area thereby facilitating sterilization. The tray can be formed of a flat plastic or metal sheet with an orifice in the flat sheet for receiving the cassette center support device and opposing handles are formed on the tray for handling the tray.
It is an object of the present invention to provide a system for sterilizing an object within a closed cassette such that when the sterilization process is completed, the sterilized object remains in the sealed cassette until use is required, thus maintaining the unit in its sterilized condition during storage.
It is also an object of the present invention to provide a novel cassette for storing the object to be sterilized during the sterilization process and for maintaining the sterilization of the device within the cassette after the sterilization process completed.
It is yet another object of the present invention to provide a connector for connecting the fluid ports of an object such as an endoscope to one of the input and/or output ports on the interior of the cassette such that when the cassette is sealed and a sterilization fluid is passed from the input port to the output port, the object is sterilized both internally and externally by causing the sterilization fluid to flow through the lumens of the object.
It is still another object of the present invention to provide a tray for insertion in the cassette such that the surface of an object is maintained in spaced relationship to minimize the sterilization contact area thereby facilitating sterilization.